The pre-procedural imaging recommendations, inter-procedural, and post-procedural imaging recommendations are very straightforward. Then we want to go through how we can do procedural performance metrics too. From 2011 to present, the directions for use have been really fluoroscopy and two-dimensional transesophageal echocardiography. In some aspects, it was always putting a catheter in a lactate appendage using fluoroscopy, changing CR angles, trying to do a measurement. We're going to 0, 45, 90, 135, hoping that we'll see the appendage and doing a measurement, and then getting device undersizing. The new recommendations is that because lactate appendage closure has become so mainstream and commercially available, and there's many, many hospitals with new operators starting, we want to give recommendations that will be broad, that will apply to many people and give them support. The general use of using baseline transesophageal echocardiography as a pre-procedural screening is not really necessary because we know that the patients are actually dehydrated. However, there is some practice of patients coming in the day of the procedure into the cath lab or to an EP lab and getting a TEE on the table. For new operators and new programs, this is actually discouraged by SCI and HRS in the sense that this obviously sometimes necessitates canceling a case if a new lactate appendage thrombosis is seen that was not previously known. It can lead to undersizing with device, and there might be challenging anatomy that might predate a different device selection that would be better optimized for that patient's anatomy. So what is the recommendation then? Well, if we don't want new operators and new programs to do on-the-table TEE, you can think about it as moving the technology forward. The TEE and pre-procedural TEE is kind of like an old cell phone. You can definitely use it, but the accuracy is not going to be as robust as the newer technologies. So what we can do is we've seen that CT is predated and is available and is widely used in TAVR pre-procedural planning. For new programs and new lactate appendage operators, everybody nowadays has access to a CT scanner if they're part of a TAVR program. What we can demonstrate is that on the bottom row, you can see that the ellipse shape of the lactate appendage is found in about 80% of patient populations. In the red line we've drawn for you where the two-dimensional TEE shows measurements as 0, 45, 90, and 135. The most important part that we can show you is that nowhere on this ellipse do we ever achieve the central image of 21.1 or the maximum diameter because the lactate appendage from the transesophageal echo in the esophagus can never get to that shape and we can never get to that angulation, whereas by CT, three-dimensionally you can. So for new programs and new lactate appendage booter operators, I recommend using pre-procedural CT as part of your planning. This will allow you to visualize any kind of anatomical defects, give you a three-dimensional view, give you optimal sizing, and more accuracy for visualization of the appendage before the case. The CT scans are also obtained in a non-fasting state, so you don't have to wait and be concerned that the patients are dehydrated, as Dr. Saw has so eloquently mentioned in her previous manuscripts that if you have an LA pressure less than 14, you're going to undersize the appendage by two-dimensional echocardiography. We also know that CT measures are generally larger by two to three millimeters compared to two-dimensional TEE, primarily because the shape of the lactate appendage is actually ellipsoid. And the recommendations also include that if there is challenging anatomies, there is value to virtual simulation, computer-aided design, and 3D printing too, to help early operators get over the early operator learning curve. What about intraprocedural? There is value to use intercardiac echo, and that's with the guidance of a pre-procedural CT planning. With pre-procedural CT planning, you can identify the main level of the lactate appendage, you can identify the landing zone, and any periapical portions of the lactate appendage that may be a risk for clot formation or perforation. You can generate fluoroscopic views on virtual simulation where the lactate appendage landing zone is going to be and the depth of the catheter placement too. Having all of these can actually facilitate the use of intracardiac echo in the procedure and negate the need for general anesthesia and avoid the use of a transesophageal echocardiography too. The recommendation is to use pre-procedural imaging with CT to optimize that efficiency. Now, if you are using intraprocedural transesophageal echo, there is some complexity during the actual TEE that requires skill and training. The 045-90-135 views tell us a lot, but many times we will not be able to see that the left circumflex artery is coming into view, and the appendages are also multi-lobed. On the bottom left-hand image, you can see this appendage actually has three lobes, and the catheter implantation will be two-thirds inferior to the circumflex artery. Being able to obtain these images on a two-dimensional transesophageal echo requires the ability to use biplane imaging and also three-dimensional echo when possible too. If not, then it will be a pre-procedural CT with intracardiac eyes. Now, patient selection is very important. As Dr. Holmstrom mentioned, there are a lot of new devices and new territory to come with class 1 indications. So where we as a community want to think about is how do we seal and what's the mechanism with all these device selections? With the FLEX, you have a plugging mechanism, amulet, lombra, and other devices. You have capping mechanisms. These will be device-specific anatomies that we've optimized for patient-centric selection. All that needs to come into consideration now as part of the pre-procedural imaging, because as we show you the left atrial appendage, you can see that their complexity actually is very, very increased compared to a TAVR valve, and that one patient on the left may be better off with capping technology, and patient on the right may be able to get a capping technology and a plugging technology, depending on what you have access to. What about post-procedural imaging recommendations? The committee had a very tough discussion regarding this and very careful consideration for patient safety. The recommendation is a pre-discharge surface echocardiogram, primarily looking for pericardial effusion. This is an example of a patient who had a FLEX implantation. Five hours later, they had a pericardial tamponade requiring emergent pericardial synthesis, and they did fine. But these are rare occurrences, less than 2% in published literature too, but it is still present, and we have to be very, very careful. Even with new device designs, these are not at zero. A pre-procedural discharge echo looking for pericardial effusions, even if it's a limited echo, will be a value and recommendation too. But what about long-term imaging? Well, the 45-day imaging follow-up for device-related trauma that Dr. Holmes mentioned earlier too, something that's actually real. On the left-hand screen, you can see a DRT at the top of the atrial surface of the FLEX device. On the right, you can see it's by CT scan too. Both modalities are fine for post-procedural imaging and looking for device-related traumas. The most important thing is having a follow-up imaging for this afterwards if you're choosing to do anticoagulation or some kind of intervention. And lastly, Dr. Kaminsky had mentioned this before too, procedural performance metrics. It was very well stated in 2016 that SCI recommended interventional implanters and electrophysiology recommendations for left-sided procedures. The same actually holds true for interventional imaging physicians. It's actually harder to pull a general cardiologist from the echo lab into the cath lab or to the EP lab to hold a TE probe to guide transeptal puncture for the first time than it is for somebody who's been in the cath lab doing PCIs for a while to transition to structural heart. So for the interventional imaging physician community, protect the safety of the device, there should be somebody who's actually had experience in guiding over 25 transeptal punctures prior to doing a left atrial condition closure because that will help maintain the safety of the device too. So in summary, a lot of thought was put into the periprocedural, intraprocedural, and post-procedural imaging recommendations because the LAA anatomy is very complex and we want everybody to have access to technology and be successful for your patients. Post-procedural imaging is not negated because it's important for patient safety to evaluate for tamponade even though it's rare. And training requirements for interventional imaging physicians are very, very important because that is a skill set that's required for transeptal puncture because as we show you in the left part, on the right side you can see left atrial appendage. There are many different sizes of left atrial appendages and knowing pre-procedural imaging intraprocedural guidance, you'll know who's an exclusion and who is a potential inclusion for these device accesses.

lactate appendage closure procedures

pre-procedural CT imaging

intraprocedural imaging

patient selection

interventional imaging physicians